1)  Found that the ETMx misaligned offsets were changed at 9am on Monday morning.  H1:SUS-ETMX_M0_TEST_P_OFFSET went from -107 to -307 suspiciously.  The YAW offset only changed by 10e-3 which is negligable.

No alogs as to why, and Kiwamu agrees that they should be set back to what they were last week.  Since the decimal places went out to the 10e-8 place unnecessarly, I've rounded to 10e-1.

2)  I zeroed a bunch of large +/- 20000 offsets that were loaded (but not turned on) in the ETMY COILOUTF OFFSETS.  Also, un-alogged as to why they were there - likely testing left over from last week??

3)  Ignored new DAMP MODE TRAMP channels all ETM/ITMs.

4)  Accepted new weekend DAMP MODE filtering on ETM/ITMs.  These likely will keep popping up but now should be set to NOT MON since commissiones have written these into GRD over the weekend.

Kyle 

Ran pump cart during this period

Kyle, Gerardo 

Pump 1 channel in "STEP" mode -> changed to 5000V "FIXED" -> Both mid station ion pumps fixed at 5000V (historically) -> May change both to 7000V fixed to be consistent with all other pumps (next maintenance day?)

J. Oberling, P. King, E. Merilh

Summary

Today we went into the PSL enclosure to increase the front end (FE) diode currents and tweak the PMC and FSS alignment.  We:

• Added ~2A of current to the 4 FE diodes and tweaked their operating temperature.  We now have 33.1 W out of the FE.
• Tweaked the PMC alignment and now have a transmitted power of 22.9 W, a reflected power of 2.4 W, and a visibility of 89.9%.
  • We will have to go back in at a later date and adjust the PMC mode matching lenses, L02 and L03, to improve the PMC transmitted power; we ran out of time today.
• Tweaked the FSS alignment to increase the RefCav transmission and now have a RefCav TPD reading of 1.47 V and a visibility of 72.3%.
• Checked the DBB RPD voltage to make sure it was above 9 V so we could continue to make measurements with the DBB.  It is at 9.53 V.  We also measured the power into the DBB along the 35 W laser path as 150 mW; this is >135 mW, so all is good.

Details

FE Diodes:

We added ~2A to the 4 FE diodes to increase the FE power, which had been slowly drifting down over the last several months (threshold for diode current adjustment is 5% drop, we were at ~7%).  Both power supplies are now feeding ~51A to the FE diodes.  We then had to optimize the temperature of the diodes to maximize the FE power.  Peter took before/after screenshots of the FE diode settings and will post them as a comment to this log.  We are now reading 33.1 W out of the PSL FE.

PMC:

We then proceeded to tweak the PMC alignment.  We adjusted both pitch and yaw on mirrors M06 and M07 and were able to get 22.9 W of transmitted power, with 2.4 W of reflected power.  This is obviously not ideal (we want reflected power to be <10% of transmitted power), but all we could do within the alotted maintenance window.  We will have to go back in at a later date and adjust the 2 mode matching lenses, L02 and L03.

Looking at the PMC RPD, it has a locked reading of -0.154 V and an unlocked reading of -1.52 V, giving a PMC visibility of 89.9%.

FSS:

We tweaked the alignment of the RefCav input periscope in both pitch and yaw and improved the RefCav transmission (as read from the RefCav TPD) from 0.75 V to 1.4 V.  We then adjusted the AOM in pitch/yaw to see if we could improve the TPD reading further.  We were able to improve the TPD to ~1.47 V.

Looking at the FSS RefCav RPD, it has a locked reading of 0.072 V and an unlocked reading of 0.260 V, giving a RefCav visibility of 72.3%.

DBB:

We opened the DBB shutters along the 35W laser path to measure the voltage on the DBB RPD; this has to be between 9 V and 11 V for proper DBB operation.  We measured it at 9.53 V.  We also measured the power into the DBB along the 35W laser path at 150 mW; this is >135 mW, so all is good here.

Greened up for engineering run. 119 channels added. 10 channels removed. H1:SUS-SR2_LKIN_P_OSC_SW2R and H1:SUS-SR2_LKIN_Y_OSC_SW2R were manually added to the exclude list. No unmonitored channels remain.

Copied compressed tarfile of logical database dump to /ligo/lho/data/conlog/h1/backups/h1conlog_dump_2015_05_26.sql.tgz. 5.8 GB.

Completes WP 5226.

Patrick, Nutsinee

... burtrestore to 05/26 06:10.

Richard, Dave

After a failure over the weekend in which DAC and ADC cards could not be detected in the I/O chassis (alog 18603), we replaced the power supply.  The removed supply will be installed in the DAQ test stand for testing.

This morning I noticed a few EXC flagged as enabled on the CDS overview.  After a roll around the room, Kissel and I cleared the LSC TPs on H1CALCS and H1SUSETMY.

Engineering Run 7

Schedule

Daily Global ER7 Run Status and Planning meeting will take place daily at 1:00pm PDT / 2:00pm CDT / 3:00pm EDT on the JRPC "TeamSpeak" channel. The plan is for a short meeting that provides updates and plans for the two interferometers and the data analysis community. This meeting will start on Tuesday, May 26, 2015.

Dan, Kiwamu, Evan

Summary

Tonight we worked on getting the interferometer back to its low-noise state. We are stable at 10 W, but there is some instability at higher powers.

Details

ITM steering

First, at 3 W we manually steered the ITMs to a good recycling gain (38 W/W), and then updated the TMS QPD offsets. We also locked the arms in green, adjusted the green QPD offsets for maximum buildup, and then updated the ITM camera references. Then we re-enabled the ITM loops in the guardian. This allowed us to power up all the way to 21 W without significant degredation of the recycling gain.

After that, we were able to consistently engage the ASC with the guardian.

Power-up issues

However, we found that at 21 W the interferomter suddenly unlocks in a matter of minutes. There seems to be no instability in the arm or sideband buildups before the lockloss. We looked at OMC DCPD signals for signs of PI, but we did not see anything ringing up during any of our short high-power locks. Some times to look at are 02:29:50, 02:59:50, 04:57:30, 06:55:00, all 2015-05-26 UTC. But any of the other 21 W locklosses in the past 12 hours follow this pattern.

We measured the OLTFs of PRCL, MICH, SRCL, and DARM before and after powering up, but they all look fine and did not change with power. For CARM, we start at 3 W with a UGF of 14 kHz with 47° of phase. Then during power-up, the electronic gain is automatically adjusted to compensate for the increased optical gain. The algorithm for this was shooting a little high, so after power-up the UGF was more like 27 kHz with 30° of phase. This is probably fine, but we adjusted the algorithm anyway, so that the UGF is placed at 19 kHz, with 45° of phase. Anyway, this did not solve the lockloss issue.

We also tried locking at some lower powers. At 15 W the interferometer lasted for about 15 minutes before unlocking. At 10 W, the lock time seems to be indefinite (at least 90 minutes).

DARM crossover

Using FM9 in ETMY L1 LOCK L (zero at 2 Hz, pole at 5 Hz), we were able to push the L1 crossover from <1 Hz to 1.7 Hz by adjusting the filter gain from 0.16 to 0.31. Measurement attached, showing before and after. This is not included in the guardian. By pushing up the crossover, the rms drive to L2 decreases from >10000 ct to about 6000 ct or so.

Other

For the record, we did not notice any kicks to the yaw of IMC REFL tonight.

The Symptoms
============

The laser is off, the chillers are running and the status screen shows either
"Interlock OK" as red, or both "Interlock OK" and "Epics Alarm" as red.



Possible Causes
===============

a) One of the safety relays in the interlock box is faulty.

b) There is a problem with the TwinCAT code controlling the chillers.

c) There is a problem with the TwinSafe code implementation.

d) Network delays in the PSL EtherCAT network accumulate to a point where
TwinSafe initiates a shutdown.

e) The turbine based flow sensor in the chiller gets stuck, registering a drop
in flow which in turn triggers the laser interlock.



The Evidence
============

a) The Dold LG5929 safety relay extension module has a mechanical life time of
20 million switching cycles and a mean time to dangerous failure of 144.3 years.
The contacts are normally open.

    Safety relays fail, they do not fail intermittently.

    Simulating an interlock box failure by switching off the interlock box
results in a sea of red on the status screen.

b) I have gone through the TwinCAT code for both chillers.  The only difference
is that there is an extra variable declared for the diode chiller.  However this
variable is never invoked in the chiller code.  The instruction sets for both the
diode and crystal chiller are the same.

c) I have gone through the TwinSafe function blocks and have not found anything
wrong with it.

d) This possibility game up because each time the laser had tripped, Patrick and
I noticed that there was 1 lost frame in the TwinCAT datastream.  However with
the laser running last week I noticed that something like 201 frames were lost
and the laser was still running.  So network delays were ruled out.

    Simulating a network delay by removing either the Rx or Tx fibre from the
Ethernet switch, results in a sea of red on the status screen.

e) The output of the flow rate sensor goes to the chiller controller via a normally
open switch.  If the flow rate is within the allowed range, the switch remains closed.
If it goes out of range, it opens and remains open until the flow rate is restored.

    For the crystal chiller, opening the flow rate switch does indeed switch off the
chiller.  Closing the flow rate switch does not switch the chiller back on automatically.
A number of fields on the status screen go red and can only be cleared by switching
the chiller back on and pressing the reset button on the status screen.

    For the diode chiller, opening the flow rate switch does switch off the chiller.
Closing the flow rate switch, turns the chiller back on.  What's more all the red
flags on the status screen go green automatically except "Interlock OK".



Conclusion
==========

Of the 5 cases outlined above, the one that seems to reproduce the observed events
is the last one.  In particular it seems that it is the flow rate sensor in the diode
chiller.